Reflex meter

ABSTRACT

The present invention relates to a reflex meter for measuring the time duration of a reflex response, such as an Achilles tendon reaction of a patient. The reflex meter of the present invention automatically provides for the measurement of the time period from the start of the reflex reaction, which is the initial muscle contraction, through the contraction of the muscle to a maximum and until the muscle has relaxed to one-half of its peak contraction. The present invention provides such a time duration measurement automatically using a switch to control the charging of a capacitor and with the capacitor charging for as long as the switch is closed. The level to which the capacitor is charged is measured to provide an output indication of time. The switch is automatically controlled to close at the beginning of the muscle contraction and to open when the muscle has relaxed to one-half of its peak contraction. The controlling of the switch may be accomplished by a mechanical switching arrangement which includes a pivoted switching arm so as to provide for the automatic closing and opening of the switch at the proper times. The controlling of the switching may also be accomplished by an electronic switching arrangement to provide for the automatic closing and opening of the switch at the proper times.

v [22] Filed:

United States Patent 1 Rieth REFLEX METER [76] Inventor: Harold F. Rieth, 2217 Harbor, Apt.

C6, Costa Mesa, Calif. 92627 Dec. 30, 1968 21 Appl. No.: 787,959

Primary Examiner Channing L. Pace AttorneySmyth, Roston & Pavitt [57] ABSTRACT The present invention relates to a reflex meter for measuring the time duration of a reflex response, such as an Achilles tendon reaction of a patient. The reflex meter 1 June 19, 1973 of the present invention automatically provides for the measurement of the time period from the start of the reflex reaction, which is the initial muscle contraction, through the contraction of the muscle to a maximum and until the muscle has relaxed to one-half of its peak contraction. The present invention provides such a time duration measurement automatically using a switch to control the charging of a capacitor and with the capacitor charging for as long as the switch is closed. The level to which the capacitor is charged is measured to provide an output indication of time. The switch is automatically controlled to close at the beginning of the muscle contraction and to open when the muscle has relaxed to one-half of its peak contraction. The controlling of the switch may be accomplished by a mechanical switching arrangement which includes a pivoted switching arm so as to provide for ,the automatic closing and opening of the switch at the proper times. The controlling of the switching may also be accomplished by an electronic switching arrangement to provide for the automatic closing and opening of the switch at the proper times.

10 Claims, 7 Drawing Figures Patented June 19, 1973 2 Sheets-Sheet 1 4 a 6 1 i 1 my, w 0 v 4 Y 22 v 1% a Z 0 j 2 1 0 1 J Z J i 5 Z w m REFLEX METER The present invention relates to a reflex meter which is used in a medical capacity to provide for a measurement of the reflex reaction of a patient. Specifically, it has been determined that there is a definite relation between the Achilles tendon reaction of a patient and the thyroid activity of that patient. For example, a normal patient, termed euthyroid, has a time duration of approximately 350 milliseconds for a specifically defined Achilles tendon reaction. A patient with a hyperthyroid condition may show a time duration of 250 milliseconds for the Achilles tendon reaction. On the other hand, a myxedema patient may show a time duration of over 500 milliseconds for the Achilles tendon reaction.

In the standard test of the Achilles tendon reaction, the patient is tapped on the Achilles tendon and the time duration between the tap, which starts the muscle contraction, and a predetermined point in the relaxation of the muscle is measured in milliseconds. The time period between the tap of the Achilles tendonand the start of the muscle contraction is relatively constant on all patients regardless of their condition, and this time between the tap of the Achilles tendon and the actual start of the muscle contraction is approximately 35 milliseconds.

Following the tap of the Achilles tendon, the muscle contracts at a steep rate and reaches a flat peak before the muscle starts to relax. The muscle relaxing period has a long trailing delay, ultimately fading to zero, and it is difficult to establish when the muscle has fully relaxed. It is also difficult to establish when the muscle has reached its peak of contraction since there is a flat response period at the peak point.

In order to alleviate these difficulties of establishing either the peak point of muscle contraction or the time when the muscle has totally relaxed, a standard procedure has been established wherein the time duration is measured from the tapping of the Achilles tendon to the point where the muscle has relaxed to one-half of its peak contraction. Testing in the past has been accomplished by plotting a graph, usually on EKG paper, showing the rise and fall of the muscle action, and the time period is determined by actually examining this graph and physically measuring the time period between the start of the test, which is the tapping of the Achilles tendon, and the time when the muscle has relaxed to onehalf of its peak contraction. This above procedure, therefore, solves the problem of measuring when the muscle has totally relaxed. Also, the above procedure solves the situation, which occurs occasionally, where the muscle never fully returns the foot to exactly the point from which it started.

The present invention relates to a reflex instrument which accomplishes the measurement of the reflex reaction and specifically provides for a measurement from the time of the contraction of the muscle to the time when the muscle has relaxed to one-half of its peak contraction, which instrument provides this measurement automatically. The reflex instrument of the present invention eliminates the necessity of plotting curves and providing for a manual examination of these plotted curves.

The reflex instrument of the present invention determines the half-point of relaxation of the muscle using either a special mechanical switch or an electronic switching method. The use of the mechanical or electronic switch, therefore, greatly simplifies the equipment necessary to perform the reflex test, and also significantly reduces the time needed by an operator of the instrument to perform the test.

The reflex instrument of the present invention is responsive only to muscle movement and, therefore, does not include the 35-millisecond period, described above, between the tapping of the Achilles tendon and the start of the muscle movement. However, since this period is basically the same for all patients, it may be added to the output reading by the operator of the instrument, or may be ignored since it is substantially constant for all patients.

As indicated above, the present invention provides for the automatic measurement of the time duration from the beginning of muscle contraction to the relaxing of the muscle to one-half of its peak contraction point, using either a novel mechanical or electrical switch arrangement. In the mechanical arrangement, a switch activating arm, which in the rest position engages a normally open switch, is pivoted about a point which is a particular distance away from the switch itself. In addition, the switch arm is deflected by a stationary pivot which is twice the distance away from the pivot point of the arm than the switch. Therefore, when the arm is activated, it rotates in addition to moving away from the switch. When the switch arm returns it engages the switch in one-half of the distance of its peak point of movement away from the switch.

In the electronic switch arrangement, the input to an electronic circuit is a variable voltage, which voltage is in accordance with the movement of a sensor arm member. The variable voltage is divided in half and both the full variable voltage and half the variable voltage is applied across a capacitor storage means and to a differential amplifier. The capacitor storage means is included in the half voltage portion of the circuit so as to maintain the half voltage input to the differential amplifier at its maximum value. When the variable voltage falls to one-half of its peak value, the inputs to the differential amplifier are the same and the output is zero, which zero output operates to open the switch.

In both the mechanical and electronic switching arrangements, the control of the switching is provided by the movement of the patients foot. Specifically, the movement of the patients foot controls the switch arm in the mechanical switching arrangement and controls the variable voltage in the electronic switching arrangement. It is to be appreciated that various mechanical and electrical methods may be incorporated in the reflex meter of the present invention, and those illustrated merely exhibit a preference. It is also to be appreciated that, although the invention has been and will be described with reference to the Achilles tendon reaction, other reactions may be measured in addition to the Achilles tendon reaction.

A clearer understanding of the invention will be had with reference to the following description and drawings wherein:

FIG. 1 illustrates the reflex instrument of the present invention positioned in relation to a patient;

FIG. 2 is a schematic drawing of the reflex instrument of FIG. 1, including a switch to control the operation of the instrument;

FIGS. 3a, 3b and 3c illustrate a mechanical switch which may be used with the instrument of FIG. 2 and specifically FIG. 3a illustrates the switch in its rest position with the switch open. FIG. 3b illustrates the switch in a fully activated position with the switch closed, and FIG. 3c illustrates the switch arm returning to open the switch once again in one-half of the peak distance shown in FIG. 3b; and

FIGS. 4a and 4b illustrate a schematic and curves describing an electronic switch which may be used with the instrument of FIG. 2, wherein the curves of FIG. 4b illustrate the input to the differential amplifier included in the circuit of FIG. 4a.

In FIG. 1 the general operation of the reflex instrument of the present invention is illustrated. As can be seen in FIG. 1, the test to be performed on a patient is the Achilles tendon reaction. The patient is kneeling on a chair with his legs stretched backwardly and hanging over the chair 12. The reflex instrument 14 is mounted on a stand 16 and is positioned to have a sensor arm 18 just touching the toe portion of the patients shoe 20. The tendon of the patients leg 10 is tapped by an operator 22 using a small hammer 24.

When the Achilles tendon is tapped, the muscle contracts and the toe of the foot of the patient swings outwardly, thereby activating the sensor arm 18. The reflex instrument 14 provides a measurement of the time duration between the reaction of the foot to the tap and until the foot has moved back to one-half of the maximum movement of the toe. This is essentially the same as saying that the instrument 14 measures the time duration between the initial contraction of the muscle and until the muscle has relaxed to one-half the peak contraction of the muscle.

The reflex instrument of the present invention does not provide a measurement between the time of the tapping of the tendon and the start of the muscle contraction, but this time duration is essentially constant for all patients and equals approximately 35 milliseconds. This value of 35 milliseconds may therefore be added to the reading of the instrument 14. For a normal patient, who is termed euthyroid, the time duration between the tapping of the tendon and the relaxing of the muscle to one-half of its peak contraction should be around approximately 350 milliseconds. If the patient has a hyperthyroid condition, the time duration may be shortened to 250 milliseconds, and if the patient is myxedema, the time duration may be over 500 milliseconds.

In FIG. 2 a schematic is shown of the instrument 14 I of FIG. 1. In FIG. 2 the instrument 14 is controlled in accordance with the operation of a switch 100, which switch is closed in response to the activation of the sensor arm 18, shown in FIG. 1, and which switch is subsequently opened when the muscle has relaxed to onehalf of its peak contraction, in a manner to be explained at a later time.

The instrument of FIG. 2 also includes a capacitor 102, which capacitor charges at a characteristic rate. Resistors 104 and 106 control the current applied to the capacitor 102. The resistor 108 is used for isolation and the resistors 104, 106 and 108 in combination with the capacitor 102 controls the voltageapplied to the gate of a field effect transistor 110. A source of voltage 112 in conjunction with a Zener diode 114 provide a voltage controlled source of power for the circuit of instrument 14.

Resistors 116 and 118 act as-a voltage divider to supply voltage through the switch 100. Additional resistors 120 and 122 control the fiow of current from the field effect transistor 110. Resistors 124, 126, plus variable resistor 128 and potentiometer 130 are used to calibrate the instrument for zeroing and full scale reading. In addition, the instrument of FIG. 10 may include a resistor 132 which is in series with the source of voltage 112 and the Zener diode 114 during the actual testing of the patient.

In order to control the instrument 14 to be either off or on and to provide a testing of the source of voltage 112, the instrument 14 of FIG. 2 includes a movable terminal and three fixed terminals designated 1, 2 and 3. All the movable terminals are in the correspondingly marked positions at the same time. The instrument 14 also includes a resistor 140 which is part of the circuitry when the switches are moved to be connected to the number 2 terminal. Finally, the instrument of FIG. 2 includes a meter 142 to provide the output indication.

In the operation of the circuit of FIG. 2, it is assumed first that the switches are connected to the number 1 terminals, which is the off position. At that time the capacitor 102 is discharged by shorting out the capacitor through the switch 138. The switches may be connected to the number 2 terminals to provide for a testing of the voltage source 112. At that time a circuit is established with the source of voltage 112, the switch 136, the resistor 140, the switch 134, the meter 142, the resistor 120, the resistor 122 and back to the source of voltage 112. If the level of the voltage source 112 is sufficient, the meter should read at either the center of the scale or higher.

The instrument of FIG. 2 may also be switched into a patient test position by activating the switches 134, 136 and 138 to be connected to the number 3 terminals. At that time, the meter 142 may be zeroed, using the movable arm of the potentiometer 130. The meter 142 may also be calibrated so that its full scale indication represents the capacitor 102 in a fully charged condition by the following procedure. The switch is closed and maintained in a closed position until the capacitor is fully charged. At that time the meter is adjusted to its full scale position using the variable resistor 128. The capacitor is now discharged by turning the switch to the off position and the instrument ready for testing by returning the switches to the patient test position.

The operation of the instrument 14 in testing a patient is as follows. First, it is to be assumed that the foot of the patient controls the closing of the switch 100 and, in addition, the switch 100 is controlled to open at a time when the muscle has relaxed to one-half of the peak contraction of the muscle. When the switch has been closed by the Achilles reaction of the patient, the capacitor 102 charges in accordance with a fixed voltage supplied to the capacitor. As the capacitor charges, the input to the gate of thefield effect transistor is in accordance with the voltage across the capacitor. The input to the gate of the field effect transistor in turn controls the output current from the field effect transistor, which output current is applied to and measured by the meter 142. The output current through the meter 142, therefore, rises in accordance with the rise of voltage across the capacitor 102.

When the switch 100 is opened, the capacitor 102 maintains its voltage and the field effect transistor 110 supplies a constant current to the meter 142. This constant current is visibly shown when the needle of the meter 142 stops rising. The operator then notes the reading which indicates time duration for the Achilles tendon reaction of the patient, or more specifically, the time duration between the muscle reaction of the patient and when the muscle has relaxed to one-half the peak contraction of the muscle.

As indicated above, the switch 100 must be controlled to close at the appropriate time and then to reopen when the muscle has relaxed to one-half of its peak contraction. The present invention describes two methods for opening and controlling this switch 100. The first method is mechanical and the second method is electronic. First, with reference to the mechanical method, FIGS. 3a, 3b and 3c illustrate this mechanical switching arrangement in its various stages of operation.

In FIGS. 3a, 3b and 3c, the sensor arm 18 of FIG. 1 is shown. The arm 18 may be spring biased outwardly by spring member 200. The switch mechanism may be contained within housing member 202, and specifically the switch mechanism includes a sensitive switch element, such as a microswitch 204, which microswitch is normally open when a control button 206 is depressed. The operation of the microswitch 204 is controlled by a pivotable switching arm 208 which is pivotally attached to the plunger 18 at pivot point 210. Fixed post members 212 and 214 plus stationary member 216 complete the structure of the switch member.

The distance from the pivot point 210 to the button 206 is one-half the distance from the pivot point 210 to the stationary pivot 216. In addition, the tension provided by the spring 200 is considerably greater than the force required to pivot the switching member 208 around the pivot point 210, but the friction provided at the pivot point 210 must be greater than the force necessary to activate the microswitch 204 through the button 206. The microswitch 204, of course, includes electrical output leads which are connected in the circuit of FIG. 2, which leads are shown by the lead members 218 and 220.

The operation of the switch of FIGS. 3a, 3band 3c is as follows. In FIG. 3a the switch is in the rest position with the sensor arm 18 fully extended. When the Achilles tendon reaction occurs, the foot provides for a movement of the sensor arm 18 inwardly. As soon as the sensor arm 18 moves in, the switch arm 208 begins to pivot around the point 210 due to the presence of the stationary pivot member 216. The button member 206 is almost immediately released since the arm 208, in addition to rotating, is moved inwardly, for example, as shown in FIG. 3b. The microswitch 204 is set so that a very' small movement provides for a closing of the normally opened microswitch.

As shown in FIG. 3b, the sensor arm 18 has been activated to its peak distance, as noted by distance X in FIG. 3b. As the muscle begins to relax from its peak contraction, the sensor arm is released from its peak position and follows the movement of the toe back toward its normal position. As shown in FIG. 3c and when the sensor arm has been returned to a distance equal to one-half of the distance X shown in FIG. 3b, the switch arm 208 again makes contact with the button 206 to activate the switch to its normally opened position. The switch mechanism, shown in FIG. 30, operates in onehalf the distance shown in FIG. 3b because the distance between the pivot point 210 and the button 206 is onehalf the distance between the pivot point 210 and stationary pivot 216. The switch mechanism shown in FIGS. 3a, 3b and 3c, therefore, provides for an automatic closing of the switch when the muscle contraction initially takes place and with an opening of the switch when the muscle has relaxed to one-half of its peak contraction.

FIGS. 4a and 4b illustrate a second electrical method of providing the same switching operation as shown in FIGS. 3a, 3b and 30. In the circuit of FIG. 4a, a potentiometer 300 has a switch arm controlled by the sensor arm 18, shown in FIG. 1. The sensor arm 18 may be biased in a downward direction by a spring member 302. As shown in FIG. 4a, the potentiometer is at its mid position but in the off position the arm of the potentiometer 300 would be at the bottom position to provide no output signal from the potentiometer 300. A voltage source 304 is coupled across the potentiometer 300 so that the movable arm of the potentiometer 300 acts as a variable voltage divider to provide an output signal in accordance with the position of the sensor arm 18.

The output from the potentiometer is applied across a resistor 306 which has a tapped midpoint. The output across the complete resistor 306 and the tapped midpoint are applied through diodes 308 and 310 to a differential amplifier 312. A capacitor 314 is used to maintain one of the inputs to the differential amplifier 312 at a fixed value in a manner to be explained later. The output signal from the differential amplifier is applied through a diode 316 to a trigger circuit 318, which trigger circuit in turn controls the operation of a switch 320 to complete the circuit between the terminals 322 and 324. The switch 320 is normally open. The switch 320 may be inserted in the circuit of FIG. 2 in place of the switch to provide for the measurement of time duration.

FIG. 4b illustrates the two inputs to the differential amplifier 312 wherein curve 326 represents the input through the diode 308 and curve 328 represents the input to the differential amplifier 312 through the diode 310.

When the sensor arm 18 is activated by the muscle contraction of the patient, the movable arm of the potentiometer 300 immediately provides an output signal which is applied to the differential amplifier 312. Actually, signals are produced at both inputs of the differential amplifier, but the input through the diode 308, as shown by the curve 326 in FIG. 4b, would initially be larger than the input through the diode 310 as shown by the curve 328. This is true since the input through the diode 310 has one-half the voltage of the input through the diode 308 and, in addition, the capacitor 316 tends to delay the signal applied to the differential amplifier 312 through the diode 310. The output signal from the differential amplifier is coupled through the diode 316 to the trigger 318, which trigger circuit is designed to operate on a rather low voltage from the differential amplifier 312, and the trigger 318 controls the switch 320 to complete the circuit between the terminals 322 and 324.

The voltage applied to the differential amplifier through the diodes 308 tends to build up to a peak point, as shown by curve 326, and once the peak point is reached, the voltage tends to drop down toward zero. This curve 326, of course, substantially duplicates the contraction and relaxation of the muscle of the patient whose Achilles tendon was just tapped. The voltage coupled to the differential amplifier through the diode 310 tends to build up to one-half of the peak value of the curve 326, as shown by the curve 328, and this value is then held due to the storage by the capacitor 314.

When the voltage coupled through the diode 308 falls to one-half the peak valve, the two inputs to the differential amplifier 312 are now substantially equal, thereby providing no output signal from the differential amplifier 312. In addition, differential amplifier 312 is designed not to produce an output signal when the voltage coupled through the diode 308 is less than the voltage coupled through the diode 310. The absence of an output signal from the differential amplifier 312 operates to open the switch 320, thereby providing an accurate measurement of the time duration between the start of the muscle contraction and until the muscle has relaxed to one-half of its peak contraction.

It is to be appreciated that other methods of measurement of the time duration may be used in place of the circuit shown in FIG. 2. For example, a system using a counter may be used to provide for a digital output indication.

The present invention provides for an instrument which automatically produces an automatic measurement of a time duration between the start of a muscle contraction until the muscle has relaxed to one-half of its peak contraction, but it will be appreciated that the time duration can be adjusted so that factors other than the start of the muscle contraction to the time of the relaxing of the muscle to one-half of its peak contraction may be measured. The present invention is only to be limited by the appended claims.

I claim:

1. An instrument for measuring the reflex reaction of a bodily portion of a patient, including:

an output indicator for providing an output indication in accordance with the variable characteristics of an input signal; first means coupled to the output indicator for providing the variable characteristic input signal to the output indicator and with the variable characteristics of the input signal in accordance with the time duration of the operation of the first means;

switch means having first and second states coupled to the first means and controlling the operation of the first means in accordance with the time between the first and second states of the switch means;

sensor means for coupling to the bodily portion producing the reflex reaction and with the sensor means responsive to such reflex reaction and with the sensor means coupled to the switch means for controlling the switch means to be in the first state upon the initial reflex reaction of the bodily portion of the patient and for controlling the switch means to be in the second state after the reflex reaction has subsided to a particular fractional level of the peak reflex reaction, and

the reflex reaction resulting from a muscle contraction of the patient and with the sensor means controlling the switch means to be in the first state upon the initial muscle contraction and with the sensor means controlling the switch to be in the second state after the muscle has relaxed to approximately one-half of its peak contraction.

2. An instrument for measuring the reflex reaction of a bodily portion of a patient, including:

an output indicator for providing an output indication in accordance with the variable characteristics of an input signal;

first means coupled to the output indicator for providing the variable characteristic input signal to the output indicator and with the variable characteristics of the input signal in accordance with the time duration of the operation of the first means;

switch means having first and second states coupled to the first means and controlling the operation of the first means in accordance with the time between the first and second states of the switch means;

sensor means for coupling to the bodily portion producing the reflex reaction and with the sensor means responsive to such reflex reaction and with the sensor means coupled to the switch means for controlling the switch means to be in the first state upon the initial reflex reaction of the bodily portion of the patient and for controlling the switch means to be in the second state after the reflex reaction has subsided to a particular fractional level of the peak reflex reaction, and

the switch means including a pivotable switch arm responsive to the sensor means and with the switch arm controlling the states of the switch means and with the switch arm controlled by the sensor means to pivot in response to the initial reflex reaction and to remain in the pivoted position until the reflex reaction has subsided to the particular fractional value of the peak reflex reaction.

3. An instrument for measuring the reflex reaction of a bodily portion of a patient, including:

an output indicator for providing an output indication in accordance with the variable characteristics of an input signal;

first means coupled to the output indicator for providing the variable characteristic input signal to the output indicator and with the variable characteristics of the input signal in accordance with the time duration of the operation of the first means;

switch means having first and second states coupled to the first means and controlling the operation of the first means in accordance with the time between the first and second states of the switch means;

sensor means for coupling to the bodily portion producing the reflex reaction and with the sensor means responsive to such reflex reaction and with the sensor means coupled to the switch means for controlling the switch means to be in the first state upon the initial reflex reaction of the bodily portion of the patient and for controlling the switch means to be in the second state after the reflex reaction has subsided to a particular fractional level of the peak reflex reaction, and

the switch means including means for producing an output signal having characteristics in accordance with the reflex reaction and with the switch means including means responsive to the output signal for controlling the state of the switch means.

4. An instrument for measuring the time duration of a physical movement of a particular bodily portion of 6s a patient, including:

patient for producing a movement of the first means in response to the physical movement of the particular bodily portion of the patient;

switch means having first and second states responsive to the movement of the first means and with the switch means in the first state in response to the initial movement of the first means and with the switch means in the second state when the movement of the first means has receded to one-half of its movement after the peak movement of the first means, and

means coupled to the switch means for providing a measurement of the time duration between the first and second states of the switch means.

5. An instrument for measuring the time duration of a physical movement of a particular bodily portion of a patient, including:

first means for coupling to the particular bodily portion of the patient and responsive to the physical movement of the particular bodily portion of the patient for producing a movement of the first means in response to the physical movement of the particular bodily portion of the patient;

switch means having first and second states responsive to the movement of the first means and with the switch means in the first state in response to the initial movement of the first means and with the switch means in the second state in response to a particular fractional level of the first means after the peak movement of the first means;

means coupled to the switch means for providing a measurement of the time duration between the first and second states of the switch means, and

the switch means including a pivotable switch arm responsive'to the first means for controlling the states of the switch means and with the switch arm pivoting in response to the initial movement of the first means and remaining in the pivoted position until the movement of the first means has receded to the particular fractional portion after the peak movement of the first means.

6. An instrument for measuring the time duration of a physical movement of a particular bodily portion of a patent, including:

first means for coupling to the particular bodily portion of the patient and responsive to the physical movement of the particular bodily, portion of the patient for producing a movement of the first means in response to the physical movement of the particular bodily portion of the patient,

switch means having first and second states responsive to the movement of the first means and with the switch means in the first state in response to the initial movement of the first means and with the switch means in the second state in response to a output signal for controlling the state of the switch means.

7. In an instrument for measuring the reflex reaction of a bodily portion of a patient and including a first means for coupling to such bodily portion and with the first means responsive to the reflex reaction of the bodily portion of the patient for producing an output from the first means in accordance with the reflex reaction, and with the instrument including:

switch means responsive to the output of the first means and having first and second states and with the switch means in the first state in accordance with the first means having an initial output response to the initial reflex reaction of the patient and with the switch means in the second state in accordance with the output of the first means at a particular fractional level after the peak output of the first means in response to the reflex reaction receding to the particular fractional level, and

the switch means including means for producing an output signal having characteristics in accordance with the reflex reaction and with the switch means including means responsive to the output signal for controlling the state of the switch means.

8. In an instrument for measuring the reflex reaction of a bodily portion of a patient and including a first means for coupling to such bodily portion and with the first means responsive to the reflex reaction of the bodily portion of the patient for producing an output from the first means in accordance with the reflex reaction, and with the instrument including:

switch means responsive to the output of the first means and having first and second states and with the switch means in the first state in accordance with the first means having an initial output response to the initial reflex reaction of the patient and with the switch means in the second state in accordance with the output of the first means at onehalf of its peak level after the peak output of the first means in response to the reflex reaction receding to one-half of its peak level.

9. In an instrument for measuring the reflex reaction of a bodily portion of a patient and including a first means for coupling to such bodily portion and with the first means responsive to the reflex reaction of the bodily portion of the patient for producing an output from the first means in accordance with the reflex reaction, and with the instrument including:

switch means responsive to the output of the first means and having first and second states and with the switch means in the first state in accordance with the first means having an initial output response to the initial reflex reaction of the patient and with the switch means in the second state in accordance with the output of the first means at a particular fractional level after the peak output of the first means in response to the reflex reaction receding to the particular fractional level, and

the switch means including a pivotable switch arm responsive to the reflex reaction and with the switch arm controlling the states of the switch means and with the switch arm pivoting in response to the initial output of the first means and remaining in the pivoted position until the output of the first means has receded to the particular fractional level after the peak output of the first means.

10. The instrument of claim 9 wherein the switch arm is pivoted by a fixed member located a particular distance from the pivot point of the switch arm and wherein the switch means includes a control member to control the states of the switch means and with the control member located half way between the fixed member and the pivot point of the switch arm.

it t t 1! t 

1. An instrument for measuring the reflex reaction of a bodily portion of a patient, including: an output indicator for providing an output indication in accordance with the variable characteristics of an input signal; first means coupled to the output indicator for providing the variable characteristic input signal to the output indicator and with the variable characteristics of the input signal in accordance with the time duration of the operation of the first means; switch means having first and second states coupled to the first means and controlling the operation of the first means in accordance with the time between the first and second states of the switch means; sensor means for coupling to the bodily portion producing the reflex reaction and with the sensor means responsive to such reflex reaction and with the sensor means coupled to the switch means for controlling the switch means to be in the first state upon the initial reflex reaction of the bodily portion of the patient and for controlling the switch means to be in the second state after the reflex reaction has subsided to a particular fractional level of the peak reflex reaction, and the reflex reaction resulting from a muscle contraction of the patient and with the sensor means controlling the switch means to be in the first state upon the initial muscle contraction and with the sensor means controlling the switch to be in the second state after the muscle has relaxed to approximately onehalf of its peak contraction.
 2. An instrument for measuring the reflex reaction of a bodily portion of a patient, including: an output indicator for providing an output indication in accordance with the variable characteristics of an input signal; first means coupled to the output indicator for providing the variable characteristic input signal to the output indicator and with the variable characteristics of the input signal in accordance with the time duration of the operation of the first means; switch means having first and second states coupled to the first means and controlling the operation of the first means in accordance with the time between the first and second states of the switch means; sensor means for coupling to the bodily portion producing the reflex reaction and with the sensor means responsive to such reflex reaction and with the sensor means coupled to the switch means for controlling the switch means to be in the first state upon the initial reflex reaction of the bodily portion of the patient and for controlling the switch means to be in the second state after the reflex reaction has subsided to a particular fractional level of the peak reflex reaction, and the switch means including a pivotable switch arm responsive to the sensor means and with the switch arm controlling the states of the switch means and with the switch arm controlled by the sensor means to pivot in response to the initial reflex reaction and to remain in the pivoted position until the reflex reaction has subsided to the particular fractional value of the peak reflex reaction.
 3. An instrument for measuring the reflex reaction of a bodily portion of a patient, including: an output indicator for providing an output indication in accordance with the variable characteristics of an input signal; first means coupled to the output indicator for providing the variable characteristic input signal to the output indicator and with the vAriable characteristics of the input signal in accordance with the time duration of the operation of the first means; switch means having first and second states coupled to the first means and controlling the operation of the first means in accordance with the time between the first and second states of the switch means; sensor means for coupling to the bodily portion producing the reflex reaction and with the sensor means responsive to such reflex reaction and with the sensor means coupled to the switch means for controlling the switch means to be in the first state upon the initial reflex reaction of the bodily portion of the patient and for controlling the switch means to be in the second state after the reflex reaction has subsided to a particular fractional level of the peak reflex reaction, and the switch means including means for producing an output signal having characteristics in accordance with the reflex reaction and with the switch means including means responsive to the output signal for controlling the state of the switch means.
 4. An instrument for measuring the time duration of a physical movement of a particular bodily portion of a patient, including: first means for coupling to the particular bodily portion of the patient and responsive to the physical movement of the particular bodily portion of the patient for producing a movement of the first means in response to the physical movement of the particular bodily portion of the patient; switch means having first and second states responsive to the movement of the first means and with the switch means in the first state in response to the initial movement of the first means and with the switch means in the second state when the movement of the first means has receded to one-half of its movement after the peak movement of the first means, and means coupled to the switch means for providing a measurement of the time duration between the first and second states of the switch means.
 5. An instrument for measuring the time duration of a physical movement of a particular bodily portion of a patient, including: first means for coupling to the particular bodily portion of the patient and responsive to the physical movement of the particular bodily portion of the patient for producing a movement of the first means in response to the physical movement of the particular bodily portion of the patient; switch means having first and second states responsive to the movement of the first means and with the switch means in the first state in response to the initial movement of the first means and with the switch means in the second state in response to a particular fractional level of the first means after the peak movement of the first means; means coupled to the switch means for providing a measurement of the time duration between the first and second states of the switch means, and the switch means including a pivotable switch arm responsive to the first means for controlling the states of the switch means and with the switch arm pivoting in response to the initial movement of the first means and remaining in the pivoted position until the movement of the first means has receded to the particular fractional portion after the peak movement of the first means.
 6. An instrument for measuring the time duration of a physical movement of a particular bodily portion of a patent, including: first means for coupling to the particular bodily portion of the patient and responsive to the physical movement of the particular bodily portion of the patient for producing a movement of the first means in response to the physical movement of the particular bodily portion of the patient, switch means having first and second states responsive to the movement of the first means and with the switch means in the first state in response to the initial movement of the first means and with the switch means in the second state in response to a particular fractional level of the firsT means after the peak movement of the first means, means coupled to the switch means for providing a measurement of the time duration between the first and second states of the switch means, and the switch means including means for producing an output signal having characteristics in accordance with the movement of the first means and with the switch means including means responsive to the output signal for controlling the state of the switch means.
 7. In an instrument for measuring the reflex reaction of a bodily portion of a patient and including a first means for coupling to such bodily portion and with the first means responsive to the reflex reaction of the bodily portion of the patient for producing an output from the first means in accordance with the reflex reaction, and with the instrument including: switch means responsive to the output of the first means and having first and second states and with the switch means in the first state in accordance with the first means having an initial output response to the initial reflex reaction of the patient and with the switch means in the second state in accordance with the output of the first means at a particular fractional level after the peak output of the first means in response to the reflex reaction receding to the particular fractional level, and the switch means including means for producing an output signal having characteristics in accordance with the reflex reaction and with the switch means including means responsive to the output signal for controlling the state of the switch means.
 8. In an instrument for measuring the reflex reaction of a bodily portion of a patient and including a first means for coupling to such bodily portion and with the first means responsive to the reflex reaction of the bodily portion of the patient for producing an output from the first means in accordance with the reflex reaction, and with the instrument including: switch means responsive to the output of the first means and having first and second states and with the switch means in the first state in accordance with the first means having an initial output response to the initial reflex reaction of the patient and with the switch means in the second state in accordance with the output of the first means at one-half of its peak level after the peak output of the first means in response to the reflex reaction receding to one-half of its peak level.
 9. In an instrument for measuring the reflex reaction of a bodily portion of a patient and including a first means for coupling to such bodily portion and with the first means responsive to the reflex reaction of the bodily portion of the patient for producing an output from the first means in accordance with the reflex reaction, and with the instrument including: switch means responsive to the output of the first means and having first and second states and with the switch means in the first state in accordance with the first means having an initial output response to the initial reflex reaction of the patient and with the switch means in the second state in accordance with the output of the first means at a particular fractional level after the peak output of the first means in response to the reflex reaction receding to the particular fractional level, and the switch means including a pivotable switch arm responsive to the reflex reaction and with the switch arm controlling the states of the switch means and with the switch arm pivoting in response to the initial output of the first means and remaining in the pivoted position until the output of the first means has receded to the particular fractional level after the peak output of the first means.
 10. The instrument of claim 9 wherein the switch arm is pivoted by a fixed member located a particular distance from the pivot point of the switch arm and wherein the switch means includes a control member to control the states of the switch means and with the control member located half Way between the fixed member and the pivot point of the switch arm. 